Soldiers say they had no warning of what they were undertaking before the morale-boosting attack began

On a recent morning deep in Ukrainian-occupied Russia, three soldiers from a Ukrainian special operations team jumped into their car, the back windscreen missing after being smashed out the previous day by explosives dropped from a Russian drone, and sped away in the direction of Ukraine.

Six hours later, they would be in Kyiv, together with a precious cargo of documents stashed in boxes piled on the back seat, the fruits of a four-day mission into enemy territory for the trio. The documents included Russian interior ministry papers and military orders, seized from official buildings in Sudzha, the town at the heart of Ukraine’s surprise Kursk operation, and from abandoned Russian trenches nearby.